1) Field of the Invention
The present invention relates to an in-cylinder fuel injection internal-combustion engine that includes a fuel injection valve that directly injects a fuel into a combustion chamber.
2) Description of the Related Art
Generally, stratified combustion or homogeneous combustion is employed in in-cylinder fuel injection internal-combustion engines.
In the stratified combustion, fuel is injected into a combustion chamber during a compression process, and an air-fuel mixture of high concentration of the fuel is unevenly distributed near an ignition plug (6). Thus, in the stratified combustion, combustion can be caused even with an air-fuel mixture that has a lower concentration of the fuel than a concentration of the fuel based on a theoretical air-fuel ratio for a whole volume of the combustion chamber. On the other hand, in the homogeneous combustion, fuel is injected into the combustion chamber during an air intake process, and the combustion is caused by making the air-fuel mixture inside the combustion chamber homogeneous.
The stratified combustion is employed when higher fuel efficiency is required. On the contrary, the homogeneous combustion is employed when higher output is required. Moreover, because the stratified combustion enables to raise a temperature of a catalyst to an activation temperature at an early stage by heating up emissions, if the stratified combustion is applied at a cold start when an engine is just started, it is also possible to improve cleaning effect of the catalyst for the emission.
Conventionally, in the in-cylinder fuel injection internal-combustion engine, two combustion modes are selectively used for the compression process and the air intake process. Therefore, a fuel injection valve or that like that can appropriately change a form of a spray of the fuel depending on the combustion mode is provided in the in-cylinder fuel injection internal-combustion engine.
A conventional fuel injection valve is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-220460. The conventional fuel injection valve includes a plurality of injection openings that are arranged at a tip of a nozzle, a plurality of fuel flow paths that continue to the injection opening, and a switching unit corresponding to each of the fuel flow paths. In the conventional fuel injection valve, the fuel injection opening from which the fuel is sprayed is chosen by switching the fuel flow path by controlling the switching unit with a control unit.
Specifically, to cause the stratified combustion, the fuel is vertically sprayed in a form of a wide-angel spray from one centrally-located fuel injection opening during the compression process. As a result, the air-fuel mixture with high concentration of the fuel is distributed near the ignition plug using a tumble stream. On the other hand, to cause the homogeneous combustion, the fuel is sprayed in the form of the wide-angle spray from two injection openings arranged on both sides of the centrally-located injection opening (or the injection opening at the center and one injection opening adjacent to the injection opening at the center) during the air intake process. As a result, the fuel is spread in the entire combustion chamber.
Thus, in the conventional technology, optimal combustion according to a state of operation is realized by using a different form of the spray for each of the compression process and the air intake process.
A related technology is disclosed in Japanese Patent No. 2650298.
However, the conventional fuel injection valve requires provision of more than one of the injection opening, more than one of the fuel flow path, the switching unit, and the control unit to control the switching unit in a body. As a result, the overall structure and functioning of the fuel injection valve becomes complicated. As a result, there are higher chances that a malfunction takes place; moreover, the manufacturing cost also increases.